D3.js curveMonotoneY() Method

Last Updated : 02 Sep, 2020

The d3.curveMonotoneY interpolator assumes that the data is sorted according to the y coordinates otherwise it sorts the data accordingly. This curve method produces a cubic spline that preserves monotonicity in x, assuming monotonicity in y.

Syntax:

d3.curveMonotoneY()

Parameters: This method does not accept any parameters.

Return Value: This method does not return any value.

Example 1:

HTML

<!DOCTYPE html> 
<html> 
<head> 
  <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/d3/4.2.2/d3.min.js"> 
  </script> 
</head> 
<body> 
  <h1 style="text-align: center; 
             color: green;"> 
    GeeksforGeeks 
  </h1> 
  <center> 
    <svg id="gfg" width="250" height="250"> 
    </svg> 
  </center> 
  <script> 
    var data = [ 
      { x: 0, y: 0 }, 
      { x: 1, y: 3 }, 
      { x: 2, y: 15 }, 
      { x: 5, y: 1 }, 
      { x: 6, y: 15 }, 
      { x: 7, y: 5 }, 
      { x: 8, y: 19 }]; 
  
    // Sorting the points by y axis 
    data.sort((a, b) => a.y - b.y); 
  
    var xScale = d3.scaleLinear() 
        .domain([0, 8]) 
        .range([25, 200]); 
    var yScale = d3.scaleLinear() 
        .domain([0, 20]) 
        .range([200, 25]); 
  
    var line = d3.line() 
      .x((d) => xScale(d.x)) 
      .y((d) => yScale(d.y)) 
      .curve(d3.curveMonotoneY); 
  
    d3.select("#gfg") 
      .append("path") 
      .attr("d", line(data)) 
      .attr("fill", "none") 
      .attr("stroke", "green"); 
  </script> 
</body> 
</html>

Output:

Example 2: Sorting the unsorted points by the x-axis then rendering the curve.

HTML

<!DOCTYPE html> 
<html> 
<head> 
  <script src= 
"https://cdnjs.cloudflare.com/ajax/libs/d3/4.2.2/d3.min.js"> 
  </script> 
</head> 
<body> 
  <h1 style="text-align: center;  
             color: green;"> 
    GeeksforGeeks 
  </h1> 
  <center> 
    <svg id="gfg" width="250" height="200"> 
    </svg> 
  </center> 
  <script> 
    var points = [ 
      { xpoint: 75, ypoint: 150 }, 
      { xpoint: 25, ypoint: 5 }, 
      { xpoint: 150, ypoint: 150 }, 
      { xpoint: 100, ypoint: 5 }, 
      { xpoint: 200, ypoint: 150 }]; 
  
    // Sorting the points by y axis 
    points.sort((a, b) => a.ypoint - b.ypoint); 
  
    var Gen = d3.line() 
      .x((p) => p.xpoint) 
      .y((p) => p.ypoint) 
      .curve(d3.curveMonotoneY); 
  
    d3.select("#gfg") 
      .append("path") 
      .attr("d", Gen(points)) 
      .attr("fill", "none") 
      .attr("stroke", "green"); 
  
  </script> 
</body> 
</html>